> \getdate
>
> \getdate{"short"}

\getdate[long]
\getdate[nil]
\getdate[false]

In context optional args are specified in brackets.

I had tried \getdate["long"], but the quotes where wrong.

It’s all
documented on the wiki:
http://wiki.contextgarden.net/Commands_with_optional_arguments

I'll look into it.

Thanks.